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Geological Society, London, Special Publications Online First

Ornamental stones of the Verbano Cusio quarry district: characterization of materials, quarrying techniques and history and relevance to local and national heritage

Giovanna A. Dino and Alessandro Cavallo

Geological Society, London, Special Publications, first published October 15, 2014; doi 10.1144/SP407.15

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© The Geological Society of London 2014 Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

Ornamental stones of the Verbano Cusio Ossola quarry district: characterization of materials, quarrying techniques and history and relevance to local and national heritage

GIOVANNA A. DINO1 & ALESSANDRO CAVALLO2* 1Earth Sciences Department, University of , Via Valperga Caluso, 35, 10125 Torino (TO), 2Department of Earth and Environmental Sciences, University of Milan-Bicocca, Piazza della Scienza, 4–20126 Milano (MI), Italy *Corresponding author (e-mail: [email protected])

Abstract: This paper reports the results of an Interreg Project (OSMATER – Sub-Alpine Obser- vatory Materials Territory Restoration) that investigated the present and historical quarrying and processing activities in the cross-border area between the Ossola Valley (Italy) and the Canton (), and the use of dimension stones in local and national architecture. These materials are in many ways unique for their abundance and lithological variety. In the past, their extraction, processing and application characterized in a decisive way the architectural and con- structive culture, both in terms of prestigious architecture and civil buildings, establishing a relationship between ‘stones and culture’, and ‘territory and its resources’. In recent years, many traditions of the quarrying, processing and architectural activities are losing importance and inter- est is being loss, resulting in a loss of knowledge and historical memory. The loss of this knowledge is likely to become irreversible in the short term, with the disappearance of people and social groups as depositaries of tradition. We conclude that the creation of an ‘observatory’, like OSMATER, is desirable and, indeed, essential if we want to preserve the historical memory of the stone industry of an entire production area.

This paper reports the results of the Interreg and typical of this territory (VCO) and its remark- PIC IIIA Project called OSMATER (Osservatorio able cultural and historical heritage. Sub-Alpino Materiali Territorio Restauro). The specific aim of the OSMATER project is to redis- cover the close relationships among landscape, Geological setting quarry exploitation, culture and local architecture. These relationships were developed both in the The VCO province is one of the most important Verbano-Cusio-Ossola (VCO) area (, NW Italian quarrying districts, due to the variety of the Italy) and in the Canton Ticino district (Switzer- exploited rocks (Fig. 1): from granites (e.g. Rosa land). The knowledge and the exploitation of and Bianco Montorfano) to orthogneisses local materials employed in historical and rural (Beola and Serizzo), marbles (e.g. Candoglia) and buildings are the basis for appreciable local and greenstones (Pietra Laugera). This wealth of build- widespread heritage preservation. The means for ing and ornamental stones is closely linked to the securing useful information was a census and clas- unusual geology of this area (Fig. 2): the thickest sification of rocks, quarries (both active and his- geological section (20 km) of the Alpine belt can torical – since the Roman age), monuments and be found here. This belt is formed by several construction techniques typical of the sub-Alpine nappe systems with subvertical attitude to the S in region, in order to create a documentation centre the median valley and subhorizontal to the N in through a dedicated website. The OSMATER pro- the Antigorio Valley where the deepest units crop ject represents a good chance both for the preser- out. The basement and cover units were metamor- vation of local buildings and quarries. Also, by phosed during the Alpine event under amphibolite means of VCO geo-tourism routes ‘from quarry to facies conditions. building’, there is a really important chance to From S to N, the VCO district shows two impor- improve and revitalise the tourist sector of the area tant structural domains separated by the Periadri- and to enhance understanding of the peculiarity atic lineament, here known as Canavese Line. of materials, exploitation and working techniques, These are the prealpine crystalline basement of and architectural applications, which are unique the Southern (Africa-verging belt) and the

From:Pereira, D., Marker, B. R., Kramar, S., Cooper,B.J.&Schouenborg, B. E. (eds) Global Heritage Stone: Towards International Recognition of Building and Ornamental Stones. Geological Society, London, Special Publications, 407, http://dx.doi.org/10.1144/SP407.15 # The Geological Society of London 2014. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

G. A. DINO & A. CAVALLO

Fig. 1. Main ornamental stones from the VCO area: (a) Rosa Baveno granite; (b) Bianco Montorfano granite; (c) Verde granite; (d) Candoglia marble; (e) Grigio Boden marble; (f) Palissandro Bluette marble; (g) Palissandro Blu Nuvolato marble; (h) Palissandro Oniciato marble; (i) Palissandro Classico marble; (j) Serizzo Antigorio gneiss; (k) Serizzo Sempione gneiss; (l) Serizzo gneiss; (m) Serizzo gneiss; (n) Quarzite Bianca gneiss; (o) Verde gneiss; (p) Beola Bianca gneiss; (q) Beola Favalle gneiss; (r) Beola Ghiandonata gneiss; (s) Beola Grigia gneiss; (t) Beola Isorno gneiss.

Alpine nappe systems of the Europe-verging belt. 280 My, the so-called Graniti dei Laghi) and dykes For detailed studies of this area, see Schmid et al. or stocks of the Appinite suite intrude this base- (1987), Colombo & Tunesi (1999), Boriani (2000), ment. The granites were extensively quarried in Engi et al. (2001), Boriani & Giobbi (2004), the past (Baveno, Montorfano, Alzo, Roccapietra Keller et al. (2005), Maxelon & Mancktelow (2005), and Quarna). Colombo & Cavallo (2007), Pleuger et al. (2007) The Ivrea-Verbano Zone consists of two main and references therein. units: the Kinzigite Formation and the Mafic Com- The basement of the Southern Alps includes: plex, which underwent upper-amphibolite to granu- the Serie dei Laghi (upper continental crust) to the lite facies conditions. The Kinzigite Formation is SE and the Ivrea-Verbano Zone (lower continen- a volcano-sedimentary sequence, constituted of tal crust) to the NW, divided by the subvertical prevailing metapelites, metapsammites, marbles Cossato-Mergozzo-Brissago Line. The Serie dei and quartzites with interlayered metabasites and Laghi is comprised of the metapelitic Scisti dei lenses of ultramafites (spinel lherzolites), mainly Laghi and the metapsammitic -Ceneri Zone: occurring near the Canavese Line. During the Early the contact is represented by banded amphibolites, Permian this sequence was intruded by a layered lenses of ultramafites and metagabbros (Strona Cen- Mafic Complex (peridotites, pyroxenites, gabbro- eri Border Zone). Late Variscan granites (around norites and anorthosites) and a huge body of quite Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

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Fig. 2. Geological sketch-map of the VCO area.

homogeneous amphibole-bearing gabbro (Main marbles) and a granulitic amphibole-bearing gab- Gabbro). The Mafic Complex shows granulite facies bro (Gabbro di Anzola). assemblages. The present tectonic setting of this The Alpine nappe system occurs from the middle Zone is possibly due to an early Permian trans- Ossola Valley across the border into Switzerland. tensional emplacement of the Ivrea-Verbano Zone The nappes consist of minor Permo-Mesozoic near the Serie dei Laghi (Boriani & Giobbi 2004). cover rocks and widespread pre-alpine crystal- In the Ossola Valley, rocks of the Ivrea-Verbano line basement intruded by late-Variscan gabbroic Zone are quarried to extract marbles from the and granitoid plutons. Strong Alpine metamorphic Kinzigite Formation (Candoglia and overprinting was mainly of amphibolite facies Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

G. A. DINO & A. CAVALLO condtions. Relicts of the pre-alpine or eo-alpine conditions of Alpine age. The orthogneisses history are scarce and mainly recognized in the Aus- within the Moncucco-Orselina-Isorno Zone troalpine units, Piemontese Zone and Upper Penni- are late-Variscan granites, which were meta- nic nappes (Monte Rosa). The granitoids occur both morphosed during the alpine event (Keller in the Austroalpine and Penninic basements while et al. 2005). Most varieties of Beola Stone the gabbros are absent from the basement of the belong to these units in the Beura-Cardezza, Penninic units. and area. In the middle Ossola Valley the nappe systems (5) Lower Penninic units, cropping out in the form part of the southern steep belt: the structural upper part of the Ossola Valley to the N of attitude is subvertical or N dipping due to the back- Domodossola. From top to bottom, they are thrusting over the Ivrea-Verbano Zone during late the , Lebendun and Antigorio Alpine events. nappe units; the deepest element is the Veram- In the Ossola Valley, from the SE to the NW, the pio orthogneiss. The attitude is sub-vertical following nappe systems are recognizable: to the S and sub-horizontal towards the N. The Monte Leone and Antigorio units are con- (1) Fobello-Rimella Schists, a thick shear zone stituted by prevailing granitic orthogneis- (1–2 km) in greenschist facies occurring in ses (quarried as Beola). The Monte Leone the inner border of the Sesia-Lanzo Zone, also includes polymetamorphic schists and close to the Canavese Line. The prevailing the mafic–ultramafic Cervandone-Geisspfad rock types (orthogneisses and paragneisses) complex. In the Ossola Valley it is represented are hardly recognizable due to the strong alpine by fine grained banded orthogneisses with deformation and mylonitization (Schmid et al. minor interlayered hornblende gneisses and 1987). Some varieties of the quarried Beola amphibolites. The Lebendun nappe consists Stone belong to this unit, especially in the of psephytic to psammitic siliciclastic meta- Vogogna area. sediments. The age of sedimentation is still (2) Sesia-Lanzo Zone (Austroalpine domain), debated, but the most probable age is Upper mainly represented by paragneisses with Palaeozoic (Permo-Carboniferous). The un- minor orthogneisses and metabasites (late derlain Antigorio nappe is formed by a huge Variscan protoliths); it is considered to be 1000 m thick body of Variscan orthogneisses the southern steep belt of the Dent-Blanche (quarried as Serizzo); it is connected to the system. Pioda di Crana Zone though the Wandfluh- (3) Piemontese Zone, only represented in the horn antiform, and is tectonically comparable Ossola Valley by thin layers of amphibolites, to the Leventina unit occurring eastwards. but widespread to the W (Aosta Valley), The Verampio orthogneiss is ‘mantled’ by where it comprises the Combin and Zermatt- the Schists, carbonate-poor metape- Saas Zone: both are ophiolitic units (Pleuger lites with garnet and staurolite + kyanite: et al. 2007). the supposed sedimentation age is Permo- (4) Upper Penninic units, represented by the Carboniferous/Permian, probably correlated Monte Rosa Zone and the Camughera- to the Lebendun series (Maxelon & Manckte- Moncucco-Orselina-Isorno Zone. These two low 2005). zones are separated by a continuous ophiolitic unit, the Antrona Zone, consisting of mafic The structural evolution of the Alpine nappes is and ultramafic rocks with minor calcschists. extremely complicated and it is a continuing sub- The Monte Rosa nappe is one of the most ject of discussion within the scientific community. complex alpine tectonic units of the Upper Several phases of deformation occurred during the Penninic domain, pertaining to the palaeo- Alpine event, and the most significant can be sum- European continental margin of the Tethys marized as follows, according Keller et al. (2005) ocean (Engi et al. 2001). It is composed of and Maxelon & Mancktelow (2005) with refer- a pre-Alpine metamorphic basement with ences therein. The first Alpine phases (D1 and D2) high-temperature relicts and a huge mass of are linked to the ‘nappe piling’, which produced Variscan meta-granitoids. The Camughera a succession of imbricate thrusts. These started unit is very similar to the Monte Rosa Zone under high-pressure conditions (12.5–16 kbar) at regarding rock types and tectonic evolution, relatively high temperatures (620–700 8C) and are whereas the Moncucco-Orselina-Isorno Zone associated with crustal shortening. They were dated (attributed to the Gran San Bernardo nappe) as Eocene (51–44 Ma). D2 is only a progressive consists of dominant paragneisses with minor stage of D1. These phases developed discrete shear orthogneisses, amphibolites and serpentin- zones associated with a stretching lineation and ites metamorphosed under amphibolite facies rarely visible isoclinal folds. The later phases of Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

VERBANO CUSIO OSSOLA DISTRICT STONES deformation (D3 and D4) are due to the backthrust- Fobello-Rimella mylonitic schists (Austroalpine, ing-backfolding stage related to the exhumation Vogogna area). The mineralogical composition of process and are linked to a dextral transpressive the Beola varieties is similar to Serizzo, consisting orogen-parallel component, the southern steep belt of quite homogeneous quartz, K-feldspar (ortho- formed during these deformation phases. clase or microcline), plagioclase, biotite and mus- covite. The main differences relate to the rock fabric (generally mylonitic) and to the presence of Quarried materials: characteristics accessory/secondary minerals. For details on the geology, historical uses and features of the Beola, The most important and extensively exploited see Cavallo et al. (2004b). ornamental stone from the VCO province is the The granites follow Serizzo and Beola in order of Serizzo (about 70% of the VCO stone production) commercial importance. They occur in the south- (Fig. 1j–m), a group of foliated granitoid orthog- ern VCO area, close to the entrance of the Ossola neisses. It is exploited in four main varieties: Valley between Lakes Cusio and Verbano, and Serizzo Antigorio (the most abundant), Serizzo For- the active quarries are located in the Baveno- mazza, Serizzo Sempione and Serizzo Monte Rosa Gravellona-Mergozzo area. The granites typically (Cavallo et al. 2004a). The former three types are are pink (Rosa Baveno), white (Bianco Montorfano) associated with the Antigorio nappe, whereas the or green (Verde Mergozzo) in colour (Fig. 1a–c), last occurs in the Monte Rosa Zone. The quarries and the main rock-forming minerals are quartz, K- (more than 50) are mostly concentrated in the Anti- feldspar (orthoclase), plagioclase and biotite, with gorio and Formazza valleys (Fig. 2), where the Anti- smaller amounts of hornblende and chlorite; gorio nappe has a sub-horizontal attitude and zircon and apatite are typical accessory minerals. reaches its greatest thickness (1000 m). The pro- The well known Rosa Baveno is from the late Var- tholith of the Serizzo was a Permian granitoid iscan Baveno pluton; the exploitation area is metamorphosed during the Alpine events. The restricted because of the frequent fractures and the main rock-forming minerals are quartz, K-feldspar lack of homogeneity in texture and colour. The (microcline), plagioclase (oligoclase) and biotite, white variety (Bianco Montorfano) comes from with variable amounts of muscovite and epidote quarries located in the southern foothills of the (allanite). The varieties from the Antigorio nappe little Montorfano pluton (Gravellona ). The are granitic to granodioritic orthogneisses with Bianco Montorfano sometimes contains a lot of medium grain size, marked planar foliation, augen mafic xenoliths and disseminated arsenopyrite that texture (K-feldspars up to 2 cm in length) and some- adversely affect the quality of the stone. The green times mineralogical lineation. granite (Verde Mergozzo) occurs on the north- The Serizzo Antigorio is the darkest variety, due western slope of the Montorfano. The peculiar min- to higher biotite content, and is of finer grain size eralogical composition of the Verde Mergozzo than the Serizzo Formazza. On the contrary, the granite (saussuritized albitic plagioclase, chlorite, Serizzo Sempione has a gneissic texture and a finer quartz and sericite) is due to post-emplacement grain size as a result of major Alpine deformation. hydrothermal metasomatism (Boriani 2000), which The Serizzo Monte Rosa is quarried in Anzasca modified the original white colour. The main prob- Valley: it is an augen gneiss with coarse K-feldspar lem for the exploitation of this ‘altered’ granite is porphyroclasts surrounded by discontinuous layers the presence of Fe-carbonates (ankerite) and poor of biotite. For details about the mineralogy, geo- polishing properties. chemistry, physical and mechanical properties of Another valuable group of ornamental stones in Serizzo varieties see Cavallo et al. (2004a). the VCO area is represented by marbles extensively The other important ornamental stone of the quarried since the Renaissance and used as building VCO province is the Beola (about 15% of the VCO stones in famous monuments in Lombardy. There production), a group of heterogeneous orthogneisses are two distinct marble types occurring in the with mylonitic foliation and strong mineralogical Ossola Valley: the Candoglia and Ornavasso cal- lineation, easy to split into thin slabs with hammer citic Ca-silicate marbles and dolo- and chisel, occurring in the middle Ossola Valley mitic marbles (Cavallo et al. 2004a). The Candoglia between Vogogna and (Figs 1n–t and Ornavasso marbles are found in the Ivrea- & 2). The Beola varieties (Beola Grigia, Bianca, Verbano Zone (southern Alps) (Fig. 2) in the form Ghiandonata, Striata) mainly come from the of sub-vertical isoclinal folded lenses (thickness Orselina-Moncucco-Isorno and Monte Rosa nappe 8–30 m) interlayered within the kinzigites and orthogneisses (upper Penninic, Beura- amphibolites. These coarse-grained and sometimes and Trontano Domodossola area) and, to a lesser banded or veined calcitic marbles contain small extent, from the Monte Leone nappe (lower Penni- amounts of Ca-silicates, quartz, magnetite and Fe- nic, Montecrestese-Crevoladossola area) and the sulphides. The famous Candoglia marble (extracted Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

G. A. DINO & A. CAVALLO since 1387 for the Cathedral of Milan) has medium ornamental stone blocks. The exploitation context to coarse-grain size and mainly pink colour, with of each rock variety is reported below. frequent dark-green layers due to the presence of diopside and tremolite; other accessory minerals Granites are quartz, epidote, Fe-sulphides, Ba-feldspar, bar- ite and rare phlogopite. The chromatic, textural and The first evidence of granite exploitation dates to mineralogical features are responsible for the com- the 15th century, firstly in the Montorfano area mercial varieties (pink, white, grey, veined marble). and later in the Baveno and Mergozzo quarry The Ornavasso marble (Fig. 1d, e) is less valuable sites. Granites were initially quarried exploiting than the Candoglia, due to the coarse-grain size, the local ‘prede´re’ (scree, loose rocks on a cliff, or dark grey colour (Grigio Boden) or more abundant alluvial deposits pertaining to the Toce river or dark veins (Rosa Valtoce). Minor white or grey cal- local streams) and erratic boulders. The material citic marbles (Bianco Avorio di Vallestrona and was exploited directly in situ to avoid the transport Grigio di Vallestrona) were extracted from the of huge quantities of quarry waste. From the 16th and Sambughetto quarries (Strona Valley, century the exploitation of granite increased more Ivrea-Verbano Zone). In contrast, the Crevolados- and more (an ancient picture depicts quarrying) sola marbles have a dolomitic composition. They (Fig. 3a) by means of ‘cugnere’, constituted by a come from the Mesozoic metasedimentary cover series of wide and deep holes, in which birch or tectonically interposed between the Monte Leone oak wedges were introduced. Once wet, they and Antigorio nappes (lower Penninic) (Fig. 2). At favoured the separation of the bench from the present, there is only one active quarry, which slope. Their technological evolution is the ‘pun- produces four main commercial varieties (Fig. ciotto’, a rock splitting wedge. From the 19th 1f–i) with varying colour and texture: Palissandro century quarrying using explosives (gunpowder) Bluette, Palissandro Blu Nuvolato, Palissandro became usual, ensuring excavation for national, as Classico and Palissandro Oniciato. The Crevola- well as local, supply (e.g. 82 columns of the Basil- dossola marbles have fine grain size and variable ica S. Paolo fuori le Mura in Rome). colour, due to the different amounts of phlogopite, After bench detachment, the blocks were Ca–Mg silicates (e.g. tremolite and diopside), dis- squared on the basis of preferential planes and then seminated sulphides and the different texture transported from the quarry to the working plants (foliation). by means of large wooden sledges – ‘struse’–on In the VCO province, other rock types were running routes. In the past, ‘bancali’ were used to quarried and worked as dimension stones: talc- load the blocks onto the ‘struse’: the ‘bancali’ are chlorite schists (Pietra Laugera or Pietra Ollare), long rectangular beams, possibly made using ash granulitic amphibole-bearing gabbros (Gabbro di wood, on which the blocks skidded, placed on Anzola or Nero di Anzola) and Triassic dolomitic rollers of birch wood with grooves on the ends – limestones (Pietra di Angera or Pietra di Arona). ‘curli’. Those techniques, similar to the ones For details about minor stones, see Cavallo et al. applied by Greek and Roman people, were used in (2004a, 2006). general for all the materials exploited in VCO (Adam 1994). Later the ‘binda’ (jack) or the der- rick (from 1920) was employed to raise the blocks. Quarry exploitation: historically and now The transport from the valley to the river port occurred by means of wagons towed by pairs of The VCO quarries are located at altitudes between oxen. Arriving at the port, the blocks were loaded 300 and 1300 m above sea level (a.s.l.). It is possible onto big barges and transported by river to the to indentify several areas characterized by the pres- working yard. Historically, the Mergozzo quarry ence of different materials (Figs 1 & 2): Baveno and area was similar to a ‘huge open pit mine’ (39 Mergozzo (granite); Vogogna, Trontano, Beura- open pit quarries in the Mergozzo area in 1830) Cardezza, Villadossola and Montecrestese (Beola); characterized by the presence of hundreds of work- , Formazza, and Crevoladossola ers. The stone-dressers (‘picasass’) (Fig. 3b) rep- (Serizzo) and Crevoladossola, Ornavasso and Can- resented the majority of the working class in the doglia (marble). Mergozzo community. The VCO dimension stones, because of the At present, the granite exploitation, mostly based present topography, are mostly exploited by means on the ‘slice cut’, is helped by the presence of of a hill side benching. A descending terraced natural discontinuities (‘Trincante surface’), weak exploitation method is applied from the higher alti- crystal iso-orientation planes, and sub-horizontal tudes and cutting in slices is possible where sys- cleavage surfaces (‘Pioda’). The splitting of the tematic discontinuities are present: indeed, these benches is obtained using explosives (pentrite deto- fractures assist the splitting of regular shaped nating fuse as a ‘cut-off agent’ and sometimes Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

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Fig. 3. (a) Baveno historical quarries in a picture painted by Gilberto Borromeo Arese (1815–1885). (b) An old picture portraying stone workers ‘Picasass’. gunpowder as a ‘thrust agent’). The blast holes are gneiss for elements of buildings (Antiquarium Mer- parallel, coplanar and closely spaced (30–60 cm), gozzo 1978; Rodolico 1995). During the 19th and with simultaneous blasting. The necessary ‘free 20th centuries, the development of quarrying tech- surface’ for block exploitation is, nowadays, made niques led to systematic exploitation of the Serizzi using a diamond wire machine (with the help of and Beole, applying the same methodologies used previous rock cut-offs in an ‘open’ configuration, in marble and granite quarries. Between 1960 and which guarantees the detachment after blasting). It 1970, bench splitting and secondary cutting were is also possible to cut the bench using explosives performed once or twice a year, using gunpowder and diamond wire machines together. The Cava- arranged in coplanar cylindrical holes, perpendicu- donna quarry (Bianco Montorfano granite) is one lar to the main fracture system (pioda); the detona- of the most important historical quarries that is tion was performed by means of electric detonators still active: in this location block detachment is or detonating fuses. The Beole and Serizzi trade achieved by simultaneous drilling (‘multidrill’) of outside the VCO area began only at the end of the close, parallel and coplanar holes; the typical 13th century, thanks to the opening of the Naviglio ‘Canne d’organo’ method. Grande channel, which guaranteed the stone trade in Milan and in the other important cities of Lom- Gneisses: Serizzi and Beole bardy. This direct way to Milan allowed huge barges to sail from the VCO, along the Toce River Exploitation of gneiss in the VCO area dates back to (navigable until the beginning of the 20th century), the Middle Ages, sometimes even to Roman times crossing Lago Maggiore and continuing along the (e.g. Lepontium Temple, Roldo Village) (Fig. 5c). Ticino River to reach Milan and Pavia (Fig. 4b). Until the 19th century erratic boulders and local Moreover, one of the main reasons for the develop- ‘predere’ were exploited, and quarrying techniques ment of the VCO stone trade was the presence of the were the same as for granites. This assured stone ‘Salt Way’, which connected Europe to Italy, cross- material supply for local rural buildings and villages ing the VCO area along Toce River: the salt was (e.g. Canova Village, near Crevoladossola, and locally paid for with dimension stone (which rep- Roldo Village, near Montecrestese) and for the con- resented the wealth of the VCO area). struction of local religious and historical buildings From the early 19th century, gneiss exploitation (S. Gaudenzio Church, Baceno) (Fig. 5d); Domo- and trade grew more and more. The increasing dossola city centre and Madonna di Campagna demand for already processed products led to the Church, Pallanza (Fig. 6a). In the case of the opening of new quarries and, consequently, to an Madonna di Campagna Church, supply from influx of local (and foreign) workers with conse- distant quarries was not possible: the exploitation quent population growth. The greatest development of erratic boulders was the only way to secure took place in the early 1900s, as the railway line and Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

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Fig. 4. (a) Serizzo quarry, loc. Rencio. (b) Sketch map of the river transport between VCO and plain. (c) Casino Visconti underground marble quarry. the construction of the Simplon tunnel in 1906 the company or a member of his family. In a VCO strongly helped the export of the local products. quarry, block handling is traditionally carried out However, the foreign market, especially Switzer- using a derrick, and there is usually one excavator, land, was the main reason for several problems one or two dumpers and six or seven drill machines. that affected the VCO stone industry. In 1908, The average production of a quarry is about without notice, the Swiss government imposed a 11 000 m3/year for the Serizzo and approximately unilateral excise duty (6.0 Lire/ton; Lire was the 7000 m3/year for the Beola. The typical finished Italian coin) for the Beole coming from VCO. This products for the stone market are mostly slabs meant that a protectionist policy was established (70%), kerbstones (20%) and squared blocks. with a consequent impact on the VCO industry (Chiaromonte 1985). The boosting of cement con- Marbles struction and the hard working conditions led to the closing of several quarries; but after World The marbles are exploited mainly in the Ornavasso- War II, new quarries were opened and working Candoglia area (calcitic marbles) and in the Crevo- conditions strongly improved. ladossola area (dolomitic marbles). The Ornavasso At present, the splitting of quarry benches is and Candoglia marbles occur in subvertical NE– undertaken using explosives, employing the same SW oriented lenses (thickness 7–12 m), within the techniques used for granite (Fig. 4a). The use of kinzigites of the Ivrea-Verbano Zone. The Orna- diamond wire machines (with sintered tools and vasso quarries have been active since the 14th plasticated wire), as well as explosives are, at century (Cava della Torre, Ornavasso, exploited present, the most suitable method, because of the also in the 19th century), but the first statement of production of ‘made to measure’ diamond wires, marble exploitation and application in Ornavasso adapted for different lithotypes (Dino & Fornaro area dates back to Roman times and, indeed, at the 2006). In a typical quarry, normally four people end of the 19th century an ancient Lepontinam are employed, one of whom is often the owner of necropolis (3rd century BC) was recovered. The Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

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Ornavasso quarries are contemporaneous with 15th century for construction of the Certosa di those of Candoglia (exploited for the building and Pavia (1518, the Fabbrica del Duomo di Pavia maintenance of the Cathedral of Milan, properties acquired the Crevoladossola marble quarry in of Veneranda Fabbrica del Duomo). The VCO mar- Lorgino, which was called Cava Pavia). Marble bles were preferred instead of those from Carrara, exploitation lasted till the end of the 17th century. because of easier and more direct transport from In 1620 the Veneranda Fabbrica del Duomo the quarries to the construction yard carried out on (Cathedral of Milan) started to quarry big blocks large barges, as noted above. In the same period, from Cava Pavia for the Cathedral construction. saws driven by water wheels started to be utilized At the end of the 18th century, Cava Pavia was for the production of slabs from stone blocks: this sold and, at the beginning of 19th century, the method, applied at first for the Cathedral of Milan, Geddo family started intensive exploitation to pro- allowed a significant reduction of working time duce magnesium lime for the building industry; (Moschini 2005). finally they started the production of marble slabs From the 14th–15th centuries, the Ornavasso using turbine-driven saws. and Candoglia quarries became more and more At present, quarry exploitation occurs in the important, and the extracted materials were fully northern and eastern areas of the marble body. used both as dimension stone and as raw material There are four derricks for moving stone, and the for lime production (kiln in Calmatta, near Orna- production is about 58 000 m3/year. The excava- vasso). Until the 19th century, there were only open tion technique is based exclusively on diamond pit quarries, and the marble was extracted using wire machines. sledgehammer, punciotti, chisels and gunpowder. The marble was worked directly in the quarry to avoid, as much as possible, the transport of large Stone application in buildings volumes of waste. At the end of the 19th century, all the quarries were closed because of low demand The described dimension stones are historically for marble, but the local exploitation started again widespread in public and private buildings of the at the beginning of the 20th century (before World VCO area: Beola has always been used for roofing War I). After World War II, marble exploita- and flooring, whereas Serizzo has been mainly tion started from the underground Casino Visconti used, both in blocks and slabs, for churches and quarry (Ornavasso), characterized by a cross- private buildings. Marbles have been largely used section of roughly 20 m2, and developed on four for paving, fac¸ade cladding and other architectural different levels (Fig. 4c). Initially, explosive was elements of churches or public buildings; granites applied in a reduced number of holes, but this tech- have been often used for columns, paving and nique was not suitable for marble exploitation due stairs (Blanco 1993; Rodolico 1995). to high waste. Thus from 1965, detachment of the The use of in situ stone sensibly influenced the blocks was carried out by drilling closely spaced local landscape, not only the natural (quarrying parallel and coplanar holes, and later by chain activities present on the hill side) but also the cutter. anthropogenic ‘scenery’, with buildings constructed The Crevoladossola dolomitic marble quarry is from local stones (typical in colours and shapes). located in Divedro Valley, on the left side of the Baveno, Mergozzo and Montorfano (S. Giovanni Diveria River, in Lorgino (Crevoladossola). The in Montorfano church) (Fig. 5a) are three small marble occurs as a sub-vertical lens, characterized towns closely connected because of the presence by a 100 m thickness, with 160–1708N dip direc- of granite quarries and, consequently, with several tion. The Crevoladossola marble varieties were granite buildings. The International Exhibitions of exploited for the production of masterpieces and the past two centuries (including those of Milan in construction elements for religious and civil build- 1906 and Turin in 1911) allowed the promotion of ings, especially in Milan and Pavia. The light col- VCO dimension stones not only in a local or oured varieties were used mainly for masterpieces national context, but also internationally (Borghi and sculptures, whereas the dark coloured variants et al. 2013). were mainly employed for claddings and indoor The present research was undertaken with the decoration. The first evidence of Crevoladossola aim of determining the relationships between marble exploitation dates back to the 11th–12th materials and monuments over an extended centuries. It was used mainly in Lombardy and in period; from Neolithic age to the present. The NW Italy and transport was predominantly by study allowed us to discover many artworks that barge but also later by rail, upon completion of the are generally ignored by traditional tour operators. Simplon tunnel (1906). For this VCO overview, the use of local stones in Like the Ornavasso and Candoglia marbles, rural buildings and villages also has to be high- Crevoladossola marble was largely used in the lighted (e.g. mountain huts, barns, pastures), but Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

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Fig. 5. (a) S. Giovanni in Montorfano Church. (b) Veglio village. (c) Lepontium Temple located in Roldo village. (d) S. Gaudenzio Church – Baceno. also the street furniture that characterized rural fields (Fig. 6b). These together provide a unique villages (e.g. Vogogna, Roldo and Canova) (Fig. chance to create different ‘Stone Tours’ from which 5b, c), combining local stones – mostly Beola and people can appreciate both cultural and historical Serizzo – with wood (e.g. Walser architecture, buildings and also rural elements typical of the which is protected because it represents not only valley. These need to be appraised, developed and the local architectural context, but is also typical endorsed. The close link between ‘stone-water- of local landscape and cultural change). In addi- wood’ is characteristic of the area, which should tion to the usual ‘civic centre’ applications, such be preserved in all its aspects (agriculture, quarry- as paving and roofing, as well as civil, historical ing activities, rivers and streams etc.). (Domodossola city centre) and religious buildings (San Gaudenzio Church, Baceno, and Madonna Discussion di Campagna Church, Pallanza) (Figs 5d & 6a, respectively), there are many agricultural structures The VCO dimension stones have a large lithologi- (farmhouses, stone walls, fence walls, and also ter- cal, aesthetical and physical 2 mechanical variety, racing for cultivation). Abandonment of these pro- and for this reason they were, and are, well appreci- duces progressive structural decay and damage to ated in the global market. The OSMATER project the area including hydrogeological and geotechn- focused and exploited their best uses in public and ical problems. Other structures made of stone are private buildings and highlighted their character- picturesque pillars, which support grapevines, and istics, which is one of the pillars for the exploitation vertical slabs used to delimit tracks and cultivated of local products. Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

VERBANO CUSIO OSSOLA DISTRICT STONES

Fig. 6. (a) Madonna di Campagna Church – Pallanza. (b) Vertical slabs used for track and cultivated field delimitation.

On the basis of this research, it was possible quarries (historical information, geology, exploita- to suggest five different ‘geological’ routes show- tion methods, etc.), manufacturing technologies ing the characteristic materials, information about and the uses. These potential routes are:

Fig. 7. Illustrations of the Granite geotouristic tour. Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

G. A. DINO & A. CAVALLO

Fig. 8. Illustrations of the Serizzi and Beole geotouristic tour.

† Granite route (Fig. 7): from the Baveno and treatment plants for waste material from Montorfano historical and active quarries to the granite quarry dumps (in order to obtain second remarkable S. Giovanni di Montorfano Church raw material for the ceramic and glass industries) (built using Montorfano white granite, Angera could be also interesting. It is a good opportunity stone and Ornavasso marble). Visits to two to emphasize the diversity of the use of stone;

Fig. 9. (a) CATS performance in ex Cava Donna – Mergozzo (‘Tones on the Stones’ exhibition) – picture by Confartigianato Novara-VCO. (b) Jazz music concert – Moro Serizzi open pit quarry (Tones on the Stones exhibitions) – picture by Confartigianato Novara-VCO. Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014

VERBANO CUSIO OSSOLA DISTRICT STONES

† Vogogna route: from the ancient Beola Vogogna The public and private bodies involved in the research quarries to the Vogogna historical village; were: Universities (Politecnico di Torino, Universita` † Serizzi and Beole route (Fig. 8): from the open degli Studi di Torino, Universita` degli Studi di Milano- pit quarries, taking note of the different exploita- Bicocca, Universita` degli Studi di Bologna, SUPSI – tion methods, to some interesting restored vil- CH), local trade associations (Confartigianato VCO, Camera di Commercio VCO, Assocave, Assograniti) and lages (Canova, Veglio and Marone) and to the Public Administrations (Provincia del VCO and Canton valuable Madonna di Campagna Church, Pal- Ticino). The authors want to thank all the researchers, lanza (built using Serizzo and Ornavasso public administrators and quarry enterprises involved in marble); the research. † Ornavasso route: visiting the historical marble quarries (Rosa Valtoce, Grigio Boden, Marmo References Chiaro Butino), listening to ancient tales about the marble exploitation, both at Ornavasso and Adam, J. P. 1994. L’arte del costruire presso i Romani. Candoglia (Milan and Pavia Cathedral building Materiali e tecniche. Ed. Longanesi, Milano. sites), focusing on transport by river along the Antiquarium Mergozzo 1978. Ossola di pietra nei Toce Valley, Lago Maggiore and the Ticino secoli. Stampa Tipografia Cerutti – Intra, Mergozzo. Blanco river, up to the Milan waterways (Navigli); , G. 1993. Le Pietre Ornamentali in Architettura. † La Nuova Italia Scientifica Editore, Roma. Val Vigezzo route: from the Pietra Ollare quar- Borghi, A., D’Atri,A.et al. 2013. Fragments of the ries to a local interactive museum, built with Western Alpine chain as historic ornamental stones in European funding, and crossing village Turin (Italy): a new geotouristic approach for the to examine restored secular buildings. enhancement of urban geological heritage. Geoheri- tage, 6, 41–55, http://dx.doi.org/10.1007/s12371- Furthermore, in recent years, with the growing 013-0091-7 interest in the geology and historical stone resources Boriani, A. 2000. The geo-petrological setting of the of the VCO quarry district, more and more cultural Verbano-Ossola domain in the frame of the Alps. and recreational activities have been undertaken. Quarry-Laboratory-Monument International Con- Examples are a ‘Tones on the Stones’ exhibition gress, Pavia, Italy, 1, 1–14. and music performances (Fig. 9a, b). Quarries such Boriani,A.&Giobbi, E. 2004. Does the basement of as Cavadonna, Lorgino and Moro Serizzo are loca- western southern Alps display a tilted section through tions that show interesting landscapes, whereas the continental crust? A review and discussion. Period- ico di Mineralogia, 73, 5–22. others such as Favalle (Beola), with their solid Cavallo, A., Bigioggero, B., Colombo,A.&Tunesi,A. walls, can be used for alternative outdoor activities 2004a. The Verbano Cusio Ossola province: a land of (e.g. free climbing and open air concerts). quarries in (Piedmont). Periodico di In a period characterized by a deep financial Mineralogia, 73, 197–210, Special Issue 3: a showcase crisis, many local activities connected to stone of the Italian research in applied petrology. exploitation can be adversely affected. The decline Cavallo, A., Bigioggero, B., Colombo,A.&Tunesi,A. of local tradition, as in the VCO area, connected 2004b. The Beola: a dimension stone from the Ossola to natural elements such as stone, water and wood, Valley (NW Italy). Periodico di Mineralogia, 73, has to be avoided because a place where the local 85–97, Special Issue 3: a showcase of the Italian research in applied petrology. heritage is not preserved is doomed to decline. Cavallo, A., Colombo,A.&Tunesi, A. 2006. The The loss of knowledge of local traditions (construc- “green stones” from Ossola valley (Piedmont, North- tion materials and techniques) is likely to become ern Italy): historical use, petrography, geochemistry irreversible in the short term, with the disappearance and physical properties. In: Cardu, M., Ciccu, R., of people and social groups who are the depositary Lovera,E.&Michelotti, E. (eds) Proceedings of of tradition. The creation of an ‘observatory’, like the Fifteenth International Symposium on Mine Plan- OSMATER, is desirable and, indeed, essential if ning and Equipment Selection, Torino, Italy. Fiordo we want to preserve the historical memory of an Srl, Galliate, Romentino NO, 1, 625–630. Chiaromonte important stone sector. The project underlines the , U. 1985. Industrializzazione e movimento operaio in Val d’Ossola, dall’Unita` alla prima Guerra importance of ensuring a synergy between the Mondiale. Ed. Franco Angeli Libri Srl, Milano. stone sector tradition and the natural heritage and Colombo,A.&Cavallo, A. 2007. Geological-structural resources. Public Administrations, Private Enter- sketch-map of the Ossola-Simplon area – Explanatory prises and Trade Associations must cooperate to Notes. 1906-2006-100 anni Traforo del Sempione. enhance the local stone sector, which is one of the Litografia Artistica Cartografica, Firenze. economic pillars of the VCO area, and conse- Colombo,A.&Tunesi, A. 1999. Pre-alpine metamorph- quently, of the Piedmont Region. ism of the Southern Alps west of the Giudicarie Line. 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